The southern California tricolor population, already reduced to less than 6,000 birds (2011 statewide survey), has fared poorly in 2013 due to a series of events at locations that recently supported the region’s largest colonies. In northern Los Angeles County, two sites, Holiday Lake and Fairmont Reservoir, are not supporting tricolor colonies in 2013. Holiday Lake was drained in March, 2013 to allow the Los Angeles County Fire Department to burn the senescent cattails. As of the third week of May, 2013 the basin has not been refilled and remains nearly empty; thus, there is no nesting habitat for tricolors at Holiday Lake this year. Fairmont Reservoir, approximately 10 miles to the southeast of Holiday Lake, is dry and does not provide nesting habitat. Thus, tricolor breeding at both L.A. County locations is prevented by an absence of nesting habitat this year.
Chris Wilson, the Director of Conservation Science at the Santa Lucia Conservancy, is placing radio transmitters on breeding tricolored blackbirds on the Santa Lucia Preserve, a private reserve in Monterey County. His research, which started in May, 2012 has found that tricolors on the preserve forage extensively upon the caterpillars of oak moths (Phryganidia californica) high in oak trees, which may be the first time that arboreal foraging has been documented in the species. His work has also shown that breeding tricolors may suddenly cease breeding and move to a different nearby breeding colony. Chris will continue his research in 2013.
A report by U.C. Davis ecologist Bob Meese in the spring, 2012 issue of California Fish and Game summarizes the effects of cattle egret predation on tricolored blackbird breeding colonies. Cattle egrets, which have only relatively recently expanded their range into California, have since 2006 been severely reducing the reproductive success of tricolor colonies within the foraging range of their rookery in Tulare County. This new report documents the impacts of cattle egret predation from 2006 through 2011 and considers the conservation implications of continued losses of tricolor productivity to cattle egret predation.
Results of Kelly Weintraub's 2011 field season in the Tulare Basin determining the nesting success rates of Tricolored Blackbird colonies in various nesting substrates. This report was prepared for the Fish and Wildlife Service as an annual report.
Methodology, results, and discussion of Tricolored Blackbird nesting success are included.
The results of the 2011 Statewide Survey have been released by Audubon California's Keiller Kyle, the survey coordinator.
The results show a dramatic drop in the number of tricolors statewide, from approximately 395,000 in 2008 to about 259,000 this year, a greater than 33% decrease, this despite an increase in the number of sites visited and an immense effort by 100 survey participants.
The results of this year's survey are summarized in a report from Kyle and Rodd Kelsey, the 2008 Statewide Survey coordinator. Download the report from the portal.
We thank the many volunteer observers for their dedication and hard work in helping to monitor the abundance, distribution, and breeding habitats utilized by the tricolor - California's blackbird.
Information for the Environment (ICE) staff at the University of California, Davis has recently upgraded the Tricolored Blackbird Portal to facilitate access to data, provide greater data input functionality, and to support the 2011 Statewide Survey and all future statewide surveys.
These enhancements include:
The 2011 Tricolored Blackbird Statewide Survey has arrived!!!
The 2011 statewide survey runs from Friday, April 15th through Sunday, April 17th.
Participants in the 2011 Statewide Survey should click here (http://tricolor.ice.ucdavis.edu/node/4875) to obtain additional information and to download survey materials.
We are seeking additional participants to survey both historical colony locations as well as to survey in appropriate regions for new, previously undocumented colony locations and to estimate the number of birds at occupied sites. No prior experience is necessary and any level of commitment, big or small, is welcome to help to make this year's survey as complete as possible.
To volunteer for this year's statewide survey, contact Keiller Kyle at kkyle (at) audubon (dot) org.
A new report, "Recent History and Current Status of the Tricolored Blackbird in Southern California", prepared by the Western Riverside County Multiple Species Habitat Conservation Plan Biological Monitoring Program, has just been released. The report reviews the annual abundance of breeding tricolors in southern California since 1994 and provides an update on the status of the species.
The report documents the alarming decline of tricolor abundance in southern California since 1997 and reveals the importance of Riverside County to tricolors in the entire southern California region.
The report provides suggestions for management actions that may help to reverse the decline and enhance the prospects for the persistence of the species in southern California.
In 2006, fewer than 30 cattle egrets (Bubulcus ibis) were observed for the first time preying upon the contents of nests of tricolored blackbirds in a single colony in Tulare County. During March and April, 2010, three large (> 30,000 birds each) tricolor colonies in Tulare County suffered near-total productivity losses to predation by cattle egrets, where up to 220 cattle egrets were consistently seen in tricolor colonies.
Thus, in only four years the cattle egret has become perhaps the tricolor's most serious threat to survival, and if the scope of cattle egret predation should increase beyond Tulare County (so recently a population source but now a population sink) , the tricolor could be in serious jeopardy. Cattle egrets are common, and increasing in abundance, throughout much of the Central Valley, but to date they have been documented to prey upon tricolors only in Tulare County.